/*
 * Javassist, a Java-bytecode translator toolkit.
 * Copyright (C) 1999- Shigeru Chiba. All Rights Reserved.
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License.  Alternatively, the contents of this file may be used under
 * the terms of the GNU Lesser General Public License Version 2.1 or later,
 * or the Apache License Version 2.0.
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 */

package com.feilong.lib.javassist.scopedpool;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.WeakHashMap;

import com.feilong.lib.javassist.ClassPool;
import com.feilong.lib.javassist.LoaderClassPath;

/**
 * An implementation of <code>ScopedClassPoolRepository</code>.
 * It is an singleton.
 *
 * @author <a href="kabir.khan@jboss.com">Kabir Khan</a>
 * @version $Revision: 1.4 $
 */
public class ScopedClassPoolRepositoryImpl implements ScopedClassPoolRepository{

    /** The instance */
    private static final ScopedClassPoolRepositoryImpl instance      = new ScopedClassPoolRepositoryImpl();

    /** Whether to prune */
    private boolean                                    prune         = true;

    /** Whether to prune when added to the classpool's cache */
    boolean                                            pruneWhenCached;

    /** The registered classloaders */
    protected Map<ClassLoader, ScopedClassPool>        registeredCLs = Collections
                    .synchronizedMap(new WeakHashMap<ClassLoader, ScopedClassPool>());

    /** The default class pool */
    protected ClassPool                                classpool;

    /** The factory for creating class pools */
    protected ScopedClassPoolFactory                   factory       = new ScopedClassPoolFactoryImpl();

    /**
     * Get the instance.
     * 
     * @return the instance.
     */
    public static ScopedClassPoolRepository getInstance(){
        return instance;
    }

    /**
     * Singleton.
     */
    private ScopedClassPoolRepositoryImpl(){
        classpool = ClassPool.getDefault();
        // FIXME This doesn't look correct
        ClassLoader cl = Thread.currentThread().getContextClassLoader();
        classpool.insertClassPath(new LoaderClassPath(cl));
    }

    /**
     * Returns the value of the prune attribute.
     * 
     * @return the prune.
     */
    @Override
    public boolean isPrune(){
        return prune;
    }

    /**
     * Set the prune attribute.
     * 
     * @param prune
     *            a new value.
     */
    @Override
    public void setPrune(boolean prune){
        this.prune = prune;
    }

    /**
     * Create a scoped classpool.
     * 
     * @param cl
     *            the classloader.
     * @param src
     *            the original classpool.
     * @return the classpool
     */
    @Override
    public ScopedClassPool createScopedClassPool(ClassLoader cl,ClassPool src){
        return factory.create(cl, src, this);
    }

    @Override
    public ClassPool findClassPool(ClassLoader cl){
        if (cl == null){
            return registerClassLoader(ClassLoader.getSystemClassLoader());
        }

        return registerClassLoader(cl);
    }

    /**
     * Register a classloader.
     * 
     * @param ucl
     *            the classloader.
     * @return the classpool
     */
    @Override
    public ClassPool registerClassLoader(ClassLoader ucl){
        synchronized (registeredCLs){
            // FIXME: Probably want to take this method out later
            // so that AOP framework can be independent of JMX
            // This is in here so that we can remove a UCL from the ClassPool as
            // a
            // ClassPool.classpath
            if (registeredCLs.containsKey(ucl)){
                return registeredCLs.get(ucl);
            }
            ScopedClassPool pool = createScopedClassPool(ucl, classpool);
            registeredCLs.put(ucl, pool);
            return pool;
        }
    }

    /**
     * Get the registered classloaders.
     */
    @Override
    public Map<ClassLoader, ScopedClassPool> getRegisteredCLs(){
        clearUnregisteredClassLoaders();
        return registeredCLs;
    }

    /**
     * This method will check to see if a register classloader has been
     * undeployed (as in JBoss)
     */
    @Override
    public void clearUnregisteredClassLoaders(){
        List<ClassLoader> toUnregister = null;
        synchronized (registeredCLs){
            for (Map.Entry<ClassLoader, ScopedClassPool> reg : registeredCLs.entrySet()){
                if (reg.getValue().isUnloadedClassLoader()){
                    ClassLoader cl = reg.getValue().getClassLoader();
                    if (cl != null){
                        if (toUnregister == null){
                            toUnregister = new ArrayList<>();
                        }
                        toUnregister.add(cl);
                    }
                    registeredCLs.remove(reg.getKey());
                }
            }
            if (toUnregister != null){
                for (ClassLoader cl : toUnregister){
                    unregisterClassLoader(cl);
                }
            }
        }
    }

    @Override
    public void unregisterClassLoader(ClassLoader cl){
        synchronized (registeredCLs){
            ScopedClassPool pool = registeredCLs.remove(cl);
            if (pool != null){
                pool.close();
            }
        }
    }

    public void insertDelegate(ScopedClassPoolRepository delegate){
        // Noop - this is the end
    }

    @Override
    public void setClassPoolFactory(ScopedClassPoolFactory factory){
        this.factory = factory;
    }

    @Override
    public ScopedClassPoolFactory getClassPoolFactory(){
        return factory;
    }
}
